1. Field of the Invention
This invention relates to apparatus for gathering printed signatures to compose books and, more particularly, to a shuttle conveyor for tandem delivery of unbound book sets to a stitcher station and a stitcher for simultaneous binding of the book sets. The invention also relates to a method of delivering and binding two book sets in tandem.
2. Background Art
The designations 1-up and 2-up have been used in the bindery industry to identify distinct operating modes. In the 1-up mode, printed signatures used to compose individual books are consecutively gathered, bound and trimmed serially along a bindery line.
Because high volume binding of books is a time critical operation, an interest in speed prompted the advent of the 2-up machine. The basic 2-up operation is similar to 1-up operation with the primary distinction that each 2-up signature usually consists of identically printed halves married along a common edge. After stitching, the 2-up signatures are divided to derive separate books. Because each operation in the bindery line is performed on two books simultaneously, the potential output rate is increased over 1-up operation.
The interest in overall system flexibility has in the past competed with the goal of high speed production. The flexibility potential in modern 1-up bindery systems is demonstrated in U.S. Pat. Nos. 3,899,165 (Abram et al) and 4,121,818 (Riley et al), both assigned to the assignee of this invention.
According to the systems in Abram et al and Riley et al, it is possible to individually tailor each book according to the special interests of a subscriber without time consuming and expensive line changes. Individual lines can be set to produce customized books for a specific destination with individual books potentially provided with special pages, inserts and/or customized ink jetting on selected signatures internally of the books. This eliminates otherwise burdensome and complicated sorting by postal zone required to comply with postal regulations and take advantage of attractive postal discounts; or permits easy bundling of books for the most efficient and economical non-postal delivery.
In both 1-up and 2-up systems, a single stroke of a reciprocative shuttle conveyor takes one unbound book from a gathering conveyor and presents the same at a stitching station. Upon completion of the stitching, the bound book is moved away from the stitching apparatus for trimming, etc. The system bottleneck normally occurs at the stitching station. The output speed for the line is dictated by the speed of the single book stitcher which has inherent mechanical speed limitations. High speed stitchers also represent a substantial expense.
To date, the goals of high speed production and system flexibility have been to a certain extent mutually exclusive. The use of the 2-up mode, which potentially doubles production rate, eliminates much of the system flexibility. The married pages of the 2-up signatures are usually identical. The books can be customized only in pairs in the 2-up mode.
Another major factor which makes 2-up printing and binding less desirable than 1-up for certain types of work is the press room cost of printing in the 2-up mode. For example, in the case of a 32 page four color catalog, in the 1-up mode the entire catalog can be run with a single set of eight cylinders upon a single press. This means, for example, that a run of 1 million catalogs can be produced in a single press run.
In the 2-up mode, on the other hand, the two pages of one catalog which are printed at the same time must be duplicates of one another, so two press runs of 500,000 each are required to print the 32 pages. This substantially increases plate making and make-ready costs in the press room; although this is largely compensated for by the high output rate of the 2-up bindery line.
The present invention is specifically directed to overcoming the problems enumerated above in a novel and simple manner.